This invention relates to an apparatus for removing electronic devices or components (e.g. semiconductor devices), mounted by being soldered on a printed circuit board.
Conventional apparatuses of the type described are disclosed, for example, in Japanese Patent Unexamined Publication Nos. 55-68177 and 57-91874.
More specifically, the former publication discloses an apparatus in which when an electronic device is to be removed from a printed circuit board, the operator removes solder from each lead pin of the individual electronic devices by means of a vacuum suction nozzle tip.
The latter publication discloses an apparatus in which whole of soldered portions of an electronic device is heated by a jet of melted solder in a solder bath, to melt the solder on all the soldered portions, thereby removing the electronic device from a printed circuit board.
In the former apparatus, the operator manually melts the solder on each lead pin, and then removes each electronic device. This operation is repeated, and therefore is cumbersome. Therefore, this method is not suitable for removing a large number of electronic devices.
In the latter apparatus, when the solder on the electronic devices mounted on the printed circuit board is to be melted, heating is applied only to the lead pin side of the printed circuit board, which results in a problem that much time is required for melting the solder. Furthermore, when the electronic device is withdrawn with the solder not yet fully melted, electrode walls or surfaces of through holes in the printed circuit board are damaged. To prevent this, when a heat capacity needed for melting the solder on the electronic devices is not clearly known, a heating time is made to be sufficiently long. Therefore, the removal of the electronic devices is inefficient, and besides the printed circuit board itself may be damaged by such long-time heating.